diff --git a/bytebeat_compiler.py b/bytebeat_compiler.py
index fa78b7b..f3ffcb7 100644
--- a/bytebeat_compiler.py
+++ b/bytebeat_compiler.py
@@ -42,7 +42,7 @@ DEFAULT_PARAMETERS = {
 def fetch(name: str):
 	if from_env := environ.get(name):
 		return from_env
-	else:
+	elif name != "CFLAGS_EXTRA":
 		return DEFAULT_PARAMETERS[name]
 
 def read_file(path: str) -> str:
@@ -82,13 +82,15 @@ CC = fetch("CC")
 CFLAGS = fetch("CFLAGS")
 INPUT_FILE = fetch("INPUT_FILE")
 OUTPUT_FILE = fetch("OUTPUT_FILE")
+if extra := fetch("CFLAGS_EXTRA"):
+	CFLAGS += " " + extra
 
 if __name__ == "__main__":
 	parser = ArgumentParser(description=\
 		"Substitutes supplied C (non-JavaScript!) bytebeat into the template, "
 		"then attempts to compile the instance of the template. Accepts "
-		"environmental variables `CC`, `CFLAGS`, `INPUT_FILE`, "
-		"`OUTPUT_FILE`.")
+		"environmental variables `CC`, `CFLAGS`, `INPUT_FILE`, `OUTPUT_FILE`. "
+		"`CFLAGS_EXTRA` can be used to add to default `CFLAGS`.")
 	parser.add_argument("file", type=str,
 		help="bytebeat formula file (use `-` to read from stdin)")
 	parser.add_argument("-o", "--output", default="output.wav", type=str,